import { create } from 'zustand';
import AsyncStorage from '@react-native-async-storage/async-storage';
import { useColorScheme } from 'react-native';
import { createNativeTheme, type NativeTheme, type ThemeVariant, type ColorMode } from '@picture/design-tokens/native';

// ThemeMode includes 'system' for automatic light/dark switching
type ThemeMode = ColorMode | 'system';
type Theme = NativeTheme;

const THEME_VARIANT_KEY = '@picture_app/theme_variant';
const THEME_MODE_KEY = '@picture_app/theme_mode';

interface ThemeStore {
  // State
  variant: ThemeVariant;
  mode: ThemeMode;
  currentTheme: Theme;
  isLoading: boolean;

  // Actions
  setVariant: (variant: ThemeVariant) => Promise<void>;
  setMode: (mode: ThemeMode) => Promise<void>;
  toggleMode: () => void;

  // Initialization
  loadTheme: () => Promise<void>;

  // Internal
  _updateCurrentTheme: () => void;
}

export const useThemeStore = create<ThemeStore>((set, get) => ({
  // Initial state - will be loaded from AsyncStorage
  variant: 'default',
  mode: 'system',
  currentTheme: createNativeTheme('default', 'dark'), // Default fallback
  isLoading: true,

  // Set theme variant
  setVariant: async (variant: ThemeVariant) => {
    try {
      await AsyncStorage.setItem(THEME_VARIANT_KEY, variant);
      set({ variant });
      get()._updateCurrentTheme();
    } catch (error) {
      console.error('Error saving theme variant:', error);
    }
  },

  // Set theme mode
  setMode: async (mode: ThemeMode) => {
    try {
      await AsyncStorage.setItem(THEME_MODE_KEY, mode);
      set({ mode });
      get()._updateCurrentTheme();
    } catch (error) {
      console.error('Error saving theme mode:', error);
    }
  },

  // Toggle between light and dark (not system)
  toggleMode: () => {
    const currentMode = get().mode;
    const newMode: ThemeMode = currentMode === 'dark' ? 'light' : 'dark';
    get().setMode(newMode);
  },

  // Load theme from AsyncStorage
  loadTheme: async () => {
    try {
      const [savedVariant, savedMode] = await Promise.all([
        AsyncStorage.getItem(THEME_VARIANT_KEY),
        AsyncStorage.getItem(THEME_MODE_KEY),
      ]);

      const variant = (savedVariant as ThemeVariant) || 'default';
      const mode = (savedMode as ThemeMode) || 'system';

      set({ variant, mode, isLoading: false });
      get()._updateCurrentTheme();
    } catch (error) {
      console.error('Error loading theme:', error);
      set({ isLoading: false });
    }
  },

  // Internal: Update current theme based on variant and mode
  _updateCurrentTheme: () => {
    const { variant, mode } = get();

    // Resolve actual mode (light or dark) from mode setting
    let resolvedMode: 'light' | 'dark' = 'dark';

    if (mode === 'system') {
      // This will be called from component that has access to useColorScheme
      // For now, default to dark
      resolvedMode = 'dark';
    } else {
      resolvedMode = mode;
    }

    const theme = createNativeTheme(variant, resolvedMode);
    set({ currentTheme: theme });
  },
}));

/**
 * Hook to get theme with system color scheme support
 */
export const useTheme = () => {
  const store = useThemeStore();
  const systemColorScheme = useColorScheme();

  // Determine actual mode
  let actualMode: 'light' | 'dark' = 'dark';
  if (store.mode === 'system') {
    actualMode = systemColorScheme === 'dark' ? 'dark' : 'light';
  } else {
    actualMode = store.mode;
  }

  // Get the correct theme based on actual mode
  const theme = createNativeTheme(store.variant, actualMode);

  return {
    theme,
    variant: store.variant,
    mode: store.mode,
    actualMode,
    isLoading: store.isLoading,
    setVariant: store.setVariant,
    setMode: store.setMode,
    toggleMode: store.toggleMode,
  };
};